Unit 5: Is the climate of Hong Kong also changing on a local scale?

Question 1

How has the climate of Hong Kong changed in recent decades?

Answer 1

Increase in:
1. Air temperature
number of hot nights
2. Rainfall, days of heavy rain + thunderstorms
3. Cloud cover

Decrease in:
1. Number of cold days
2. visibility
3. Wind speed
4. Amount of sunshine reaching the ground

Question 2

What are the characteristics of an urban microclimate as compared to rural areas?

Answer 2

1. larger amount of cloud cover
2. higher rainfall + air temperature
3. lower:
   relative humidity
   wind speed
   visibility
4. less amount of sunshine received on the ground

Question 3

why does an urban microclimate exist in Hong Kong

Answer 3

1. heat island effect : an urban area which has a higher mean air temperature than the surrounding rural areas
2. dense buildings lower wind speeds
3. high concentration of air pollutants reduces visibility
4. lack of vegetation and water surfaces lowers relative humidity
5. favourable conditions leading to more cloud cover and rainfall
6. suspended particulates lower the amount of sunshine received

Question 4

heat island effect definition

Answer 4

an urban area which has a higher mean air temperature than the surrounding rural areas

Question 5

reasons for heat island effect

Answer 5

1. pollutants and water vapour -> a blanket effect -> prevents heat from escaping
2. urban activities (air-conditioning + transport) -> man-made heat
3. concrete + asphalt of buildings
   day: absorb heat + warm up rapidly
   night: heat store in buildings + road materials is released
4. taller + more densely packed buildings in urban areas block wind flow + trap heat in urban areas
5. lack of vegetation cover + wet surfaces (e.g rivers + lakes) due to reclamation -> less cooling effect from evapotranspiration

Question 6

dense buildings lower wind speeds

Answer 6

dense buildings -> increase the surface roughness + fictional drag on winds -> wind speed lower in urban areas near the ground

Question 7

how does a high concentration of air pollutants reduces visibility

Answer 7

all pollutants from burning fossil fuels cannot be dispersed -> accumulate in urban areas in low wind speeds
nitrogen oxide + volatile organic compounds (VOCs) may have a chemical reaction with sunlight -> form ozone
accumulation of
1. ozone
2. fine particulates
3. other air pollutants
in the lower layer in the atmosphere -> form smog

Question 8

air pollutants from fossil fuels

Answer 8

1. nitrogen oxides
2. sulphur dioxide
3. carbon monoxide
4. suspended particles

Question 9

how do you form ozone from sunlight

Answer 9

nitrogen oxide + volatile organic compounds (VOCs) may have a chemical reaction with sunlight -> form ozone

Question 10

how is smog formed

Answer 10

accumulation of
1. ozone
2. fine particulates
3. other air pollutants
in the lower layer in the atmosphere -> form smog

Question 11

why does a lack of vegetation and water surfaces lowers relative humidity

Answer 11

the supply of moisture from vegetation is limited

Question 12

favourable conditions leading to more cloud cover and rainfall

Answer 12

1. high temperature -> air heats up -> rising air currents
2. winds hit tall buildings -> forced to rise higher up into the atmosphere -> higher concentration of air pollutants -> condensation nuclei leading to cloud formation

Question 13

suspended particulates lower the amount of sunshine received

Answer 13

more suspended particulates + cloud cover
cloud + rain reflect solar radiation back into space

Question 14

What are the mitigation measures of climate change in Hong Kong?

Answer 14

1. Use energy resources with low GHG emissions
2. Promote low-carbon transport
3. Increase energy efficiency in buildings and infrastructure

Question 15

What are the adaptation measures of climate change in Hong Kong?

Answer 15

1. improve drainage management + flood control
2. better urban designs
3. build flood walls
4. enhance slope safety

Question 16

examples of using energy resources with low GHG emissions

Answer 16

mitigation
1. phase down coal for electricity generation
2. increase share of natural gas
3. adopting renewable energy sources, such as:

1. installing solar panels on roofs
2. buying excess solar power from the public
3. using landfill gas to produce energy

Question 17

examples of promoting low-carbon transport

Answer 17

mitigation
1. expand railway networks to lower the energy used per passenger
2. encouraging the use of electric + hybrid cars

Question 18

examples of increasing energy effects in buildings + infrastructure

Answer 18

mitigation
1. promote rooftop + vertical greening -> help lower air temperatures
2. introduce district cooling systems -> reduce the use of air conditioning

Question 19

examples of improving drainage management and flood control

Answer 19

adaptation
1. construct underground drainage systems
2. construct storage tanks to prevent densely populated areas from flooding

Question 20

mitigation meaning

Answer 20

reducing risk of loss

Question 21

examples of better urban designs

Answer 21

adaptation
1. contrast rain garden -> capture + filter rainwater
2. build storage tank and storage lakes -> capture + store storm water
-> lower surface runoff
3. construct porous pavement -> increase infiltration

-» more water stored for future use
4. revitalise river channels to provide habitats to wildlife

Question 22

examples of building flood walls

Answer 22

build flood walls in low-lying coastal areas to prevent coastal flooding

Question 23

examples of enhancing slope safety

Answer 23

adaptation
1. regularly check + maintain governments slopes
2. provide guidelines and advisory services of slope maintenance to private slopes

Question 24

examples of protect and enhancing ecosystems

Answer 24

adaptation
1. expand country -arks and marine parks
2. promote urban forestry to provide habitats for wildlife + help reduce heat island effect